Why I need two interface for acm?

[mttbx]

This is not a bug report. I'm newbie to USB driver. I tried your demo, and I found there's two interfaces to support acm. And the endpoint of the first interface wasn't registered (CDC_NTF_EP). I noticed that you grouped these two interfaces together (USB_DTYPE_INTERFASEASSOC), why did you do that? Can you help me out?

[dmitrystu]

Hi.
This for the generic CDC driver under Windows. See MS Docs

[mttbx]

Thanks